Best method of learning the English language

When it comes to learning Russian, I have a plethora of resources at my disposal, but I would like to know the best way a Russian-speaking person can go about learning or improving their English.

My father-in-law is Ukrainian and has been trying to learn English for years. He knows about as much English as I do Russian (about 30-40%) and struggles with life because he cannot communicate with the people around him... I would like to help him as much as I can because we cannot talk with each other because of the language barrier (which we're trying to take down, from both sides). Is there a Russian version of Rosetta or Pimsleur or equivalent for learning English?